Known kneading machines for both domestic and industrial use comprise a container, which is typically made of stainless steel, wherein a rotor provided with a plurality of mixing paddles is arranged; the rotor is rotatably restrained to the shaft of an electric motor.
In order to make an alimentary dough, a certain amount of ingredients in the solid state, such as mixtures of flour and/or meals, is introduced in the container, wherein they are mixed in a continuous manner by rotating the rotor during the preparation of the dough. In the case of the preparation of alimentary doughs for bread or pastry products, the ingredients in the solid state also comprise yeast.
During the mixing step the container is generally closed by a lid and ingredients in the liquid, e.g. water, solid and/or powdered state necessary to the preparation of the desired dough are gradually added to the ingredients in the solid state. The mixing step continues until a smooth dough suitable to be subjected to further processing is obtained.
The European patent EP 2554051 in the applicant's name describes for example a kneading machine for alimentary doughs comprising a container provided with a tight lid and a rotor arranged proximate to or at the bottom of the container and rotatably restrained about a vertical rotation axis. The kneading machine also comprises a plurality of spray nozzles restrained to the lid, which are arranged and oriented so as to direct their jets towards the bottom and the peripheral walls of the container. The rotor comprises a flat base formed of a plurality of arms and a plurality of mixing paddles extending from the arms predominantly perpendicular thereto. The free ends of the paddles are bent towards the rotation axis of the rotor and inclined relative to its flat base, as well as relative to a plane perpendicular thereto and passing through the rotation axis. Thanks to these characteristics, it is possible to generate swirling mixing movements on planes that are perpendicular to each other, thus promoting mixing of the particles of the mixtures of flours and/or meals with the ingredients injected by the nozzles, and hence enhancing homogenization and hydration of the dough.
Once the preparation step is finished an alimentary dough must be discharged from the container of a kneading machine in order to proceed to further steps and/or processing of the production process. At an industrial level this operation is carried out in an automated way.
It is known that a finished alimentary dough has a remarkable compactness and a generally sticky consistency, thereby making it difficult to discharge it from the container of a kneading machine. While in kneading machines wherein the rotor is rotatably arranged about an horizontal axis the rotor can be removed before discharging the dough, in kneading machines having a vertical axis as the kneading machine of the
European patent EP 2554051 this is not possible because the rotor is under the dough relative to the discharging direction.
Consequently, dough residues often remain inside the container of a kneading machine with a vertical rotation axis, which require cleaning operations after discharging of the dough before proceeding to a new preparation step.